This invention relates to improvement for scanning apparatus and particularly improvement for scanning apparatus used in barcode devices.
Photoelectric technology has been developed and evolved to become a mature technique now. It has been widely employed in a lot of fields such as data transmission, sensor application, medical care, and the like. Using in barcode applications is even more popular than in other areas. In the barcode applications, a barcode device has a laser light source projecting laser light to a reflection mirror of a scanning apparatus. The reflection mirror moves with the scanning apparatus and projects the laser light to a barcode attached to an object. In the mean time, the barcode device reads the barcode synchronously.
The optical scanner in the barcode device equipped with light type scanner is now available in the market place. There are a number of patents being announced. For instance, U.S. Pat. No. 5,168,149 discloses a scanning device which employs the elasticity and inertia of Mylar strip to drive the reflection mirror of the scanning device moving reciprocally for the projecting laser light spot hit the reflection mirror to become a straight line, or uses magnetic force of a strut-shaped magnet and a ferrite frame to generate reciprocal motion to drive the reflection mirror for the laser light spot projected on the reflection mirror to become a straight line for scanning the barcode on the object effectively.
However production of the scanning devices set forth above needs high degree of precision. Control of the physical property of the materials is difficult. Manufacturing process is complicated and assembly of the product is time-consuming. Furthermore, accuracy of laser light reflecting on the barcode is difficult to adjust. The device is also easier to get breakdown or malfunction. All this creates a lot of problems in production and utilization.
Applicant has previously submitted a design which uses a spiral hairspring structure. The hairspring may produce a circular movement and drive a spindle. There is a holding seat mounted on the spindle for holding a reflection mirror. A magnet is fixed at two sides or the rear side of the holding seat. When a coil is magnetized and generates magnetic force, a corresponding force will be generated on the fixed magnet to produce strain on the spiral hairspring. When the magnetic force on the coil is absent, the spiral hairspring will have a counter reaction force and inertia to move reciprocally to drive the spindle. Then the reflection mirror and spindle will turn concentrically and synchronously. The light spot projected on the reflection mirror will scan to form a straight line. Hence if the coil is magnetized at suitable time, the movement will become continuously.
However the construction of the hairspring and spindle is relatively complex. It also needs high degree of precision. Material selection and fabrication are more difficult. Material variation for same movement angle is greater and the response is slower.
In view of aforesaid disadvantages, it is therefore an object of this invention to provide an improvement that employs a high elasticity coefficient material as driving force for scanning operation. Material variation for same movement angle during scanning operation is less. Response time is faster. As a result, barcode scanning speed may be increased.
Another object of this invention is to simplify the structure. There is no spindle. Production process is simpler and assembly is easier. There is also no friction incurred during movement. It is thus a more desirable design of scanning apparatus for the barcode devices.
In order to achieve aforesaid objects, in this invention there is a twist means which includes a formed member made from a material of high elasticity coefficient such as silicon rubber, rubber or the like. When a driving means is magnetized, the generated magnetic force will produce a corresponding force against magnetic elements and twist the formed member. When the magnetic force is absent, the formed member will move a reflection element concentrically results from the counter reaction force and the inertia thereof And light will be projected on the barcode of an object to be scanned.